UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

NATIONAL VEHICLE AND FUEL EMISSIONS LABORATORY

2000 TRAVERWOOD DRIVE

ANN ARBOR, MI 48105-2498

 OFFICE OF

AIR AND RADIATION

February 18, 2014

MEMORANDUM

SUBJECT: Revised PBMS Flow Charts from April 18, 2013 Meeting with American Petroleum Institute (API) Test 

Methodologies Workgroup

FROM: Joe Sopata, Chemist

USEPA/OAR/OTAQ/CD/FCC

TO: EPA Docket # EPA-HQ-OAR-2011-0135

This memo corrects the flow charts that were provided to the docket documenting a meeting held on April 18, 2013 between 

representatives of API Test Methodologies Workgroup and the United States Environmental Protection Agency (EPA) to discuss 

EPA’s Performance Based Analytical Test Method Approach included in the proposed rule entitled, “Control of Air Pollution from 

Motor Vehicles: Tier 3 Motor Vehicle Emission and Fuel Standards”. The meeting attendees from API Test Methodologies 

Workgroup included David Lax (API), Janice Raburn (BP), Kathryn Brtko (BP), Sonia Bain (Marathon), John Rizzo (Marathon), 

Richard Stanley, Alex Lao, Frank Disanzo (ExxonMobil), Barbara Schroeder (Shell), Al Verstuft (Chevron) and Kishore Nadkarni, , 

and from EPA included Joe Sopata, Robert Anderson, Winifred Okoye, and John Weihrauch.

The discussion topics during this meeting included background, proposed qualification criterion, statistical quality control 

requirements, implementation dates and Agency approval options which were presented in detail in the preamble and regulations of 

the Tier 3 proposal. In addition, meeting attendees from the API Test Methodologies Workgroup requested EPA provide flow chart 

examples of qualification requirements for Absolute Fuel Parameters and Method Defined Fuel Parameters. During the comment 
period for the proposed rulemaking, API and AFPM provided editorial comments for the Absolute Fuel Parameter flow chart and 

requested that these flow charts be corrected in the docket for the Tier 3 final rulemaking. In addition, during the comment period for 

the proposed rulemaking, several comments were made on the criterion for the reference installation of the designated test method as 

well as the precision criterion for method defined fuel parameters in which EPA agreed. Thus the flow chart example for method 

defined fuel parameter was corrected to reflect the changes applicable to method defined fuel parameters in the Tier 3 final rule. The 

corrected flow charts for both the Absolute Fuel Parameter and Method Defined Fuel Parameter are attached to this memorandum but 

are not intended to cover all aspects of the Performance Based Analytical Test Method Approach requirements. EPA encourages

review of both the Tier 3 final rule’s preamble and regulations for details not covered in these flow charts. 
Flow Chart Example: Absolute Fuel Parameter (Absolute) - Sulfur in Gasoline 

Note: Fuel parameters categorized as “Absolute” are sulfur in gasoline and sulfur in 

butane, besides sulfur in diesel fuel (VCSB – Voluntary Consensus Standards Body)

YES YES

NO

 

 NO NO

YES

Is Alternative Test 

Method a Voluntary

Consensus Standard

Body (VCSB Method)?

Precision - the maximum allowable standard 

deviation of 20 test results on a 10 ppm gasoline 

would be 0.95 ppm.

Accuracy – the average of 10 consecutive results 

on a 1-10 ppm gravimetric sulfur standard cannot 

differ by more than 0.71 ppm from the ARV of the 

standard and the average of 10 consecutive results 

on a 10-20 ppm gravimetric sulfur standard cannot 

differ by more than 1.00 ppm from the ARV of the 

standard.

Method Qualified

Lab determines if 

ASTM D6708 

reveals that 

sample-specific 

biases cannot be 

determined as 

random?

Method 

Disqualified.

Method 

Disqualified
Flow Chart Example: Method-Defined Fuel Parameter (Method-Defined) 

Aromatics in Gasoline: Note: All other fuel parameters besides sulfur in diesel fuel, 

sulfur in gasoline, and sulfur in butane currently designated in our gasoline and diesel 

fuel programs are Method-Defined 

(VCSB – Voluntary Consensus Standards Body)

YES NO

YES NO YES NO

Obtain use of a Reference Installation of 

Designated Test Method (DM):

1) DM near middle distribution of within the 

middle 50% of the distribution of 

measurements for 3 out of 5 exchanges of 

either the industry or commercially available 

monthly ILCC program for at least five 

months.

2) DM has been shown to be in statistical 

control for a period of 5 months. 

Precision - the maximum 

allowable standard deviation of 

20 test results on a 32 volume 

percent aromatics gasoline 

would be 1.11 volume percent.

Is Alternative Test 

Method a Voluntary

Consensus Standard 

Body (VCSB) Method?

VCSB determines if use of ASTM 

D6708 yields a null result compared 

to designated test method (DM)?(**).

Lab determines if ASTM 

D6708 reveals that samplespecific biases cannot be 

determined as random?

Use 

Alternative 

Test Method 

result w/o 

correlation.

VCSB uses 

ASTM D6708 

to determine 

correlation 

equation to 

DM.

Method 

Disqualified

.

Same as ** but 

Lab also 

determines if 

the cross 

method 

reproducibility

(Rcm) is ≤ 70% 

of published R 

of DM.